A2Ar-dependent PD-1+ and TIGIT+ Treg cells have distinct homing requirements to suppress autoimmune uveitis in mice.

The proper function of regulatory T cells (Tregs) to suppress inflammation requires homing to the correct tissue site. Resolution of autoimmune uveitis generates distinct programmed death receptor 1 (PD-1+) and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT+) Tregs in an adenosine 2A receptor (A2Ar)-dependent manner found in the spleen. Where and how these Tregs migrate from the spleen to prevent uveitis is not known. In this work, we show that A2Ar-dependent Tregs migrated to the eye and secondary lymphoid tissue and expressed chemokine receptor (CCR)6 and CCR7. Suppression of autoimmune uveitis required CCR6 and CCR7 expression for TIGIT+ Tregs but not PD-1+ Tregs. Moreover, stimulation of A2Ar on T cells from patients showed a decreased capacity to induce TIGIT+ Tregs that expressed CCR6 or CCR7, and PD-1+ Treg that expressed CCR6. This work provides a mechanistic understanding of the homing requirements of each of these Treg populations. Importantly, this work is clinically relevant because patients with chronic autoimmune uveitis are unable to induce the Treg populations identified in mice that home to the target tissue.

Effects of Subcutaneous Repository Corticotropin Gel Injection on Regulatory T Cell Population in Noninfectious Retinal Vasculitis.

AIM: To evaluate the effect of repository corticotropin injection (RCI) on regulatory T cell population in patients with noninfectious retinal vasculitis. PATIENTS AND METHODS: Patients with active noninfectious retinal vasculitis were included in a prospective nonrandomized open-label study. RESULTS: Eighteen patients (33 eyes) were included in the study. Eleven (61.1%) patients [20 (60.6%) eyes] and 7 (38.9%) patients [13 (33.3%) eyes] were in the responsive and non-responsive groups, respectively. We did not find any statistically significant difference within the PPP-R group, within the PPP-NR group, or between these two groups in regard to regulatory T cell population. No significant systemic or ocular complications were found. CONCLUSION: RCI may be a complementary treatment in patients with non-infectious retinal vasculitis with or without uveitis. This study did not demonstrate an increase in regulatory T cell population in patients with noninfectious retinal vasculitis.

TIGIT+ A2Ar-Dependent anti-uveitic Treg cells are a novel subset of Tregs associated with resolution of autoimmune uveitis.

Regulatory T cells (Tregs) are necessary to prevent autoimmune disease. As such, stable FoxP3 expression is required for the proper function of Tregs in the control of autoimmune disease. Different Treg subsets that utilize different mechanisms of suppression have been identified. The T-cell immunoglobulin immunoreceptor tyrosine-based inhibitory motif (TIGIT) is a relatively new Treg cell marker that has a suppressive function. We have previously identified the adenosine 2A receptor (A2Ar) as a requirement for the emergence of Tregs following resolution of autoimmune disease. Using a FoxP3-GFP-Cre reporter mouse, we identify FoxP3 and 'exFoxP3' cells, show FoxP3 and not exFoxP3 cells are suppressive. We further show FoxP3 cells express TIGIT, and are induced through A2Ar in healthy volunteers, but not patients with autoimmune disease. Furthermore, we show Tregs emerge in the target tissue at the onset of autoimmune disease in an A2Ar-dependent manner. In summary, we identify a novel subset of TIGIT+ Tregs that are induced through stimulation of the A2Ar.